As measures to improve convenience for telephone users and to correct the cost difference between long distance and short distance calls, a late night discount was introduced and the hours covered by the night-time call discount extended in 1980 (Showa 55). The late night discount (60% reduction) applied from 9 PM to 6 AM and the night-time discount (40% reduction) applied from 7 PM to 9 PM and 6 AM to 8 AM.

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